From 8606, backdoor roth IRA reporting
https://www.irs.gov/pub/irs-prior/f8606--2020.pdf
Use Form 8606 to report:
- Nondeductible contributions you made to traditional IRAs.
- Distributions from traditional, SEP, or SIMPLE IRAs, if you have ever made nondeductible contributions to traditional IRAs.
- Conversions from traditional, SEP, or SIMPLE IRAs to Roth IRAs.
- Distributions from Roth IRAs.